PROJECT SUMMARY The postdoctoral Training Program in Endocrinology at the Massachusetts General Hospital provides intensive research experience in basic or clinical investigation, complemented by a didactic component appropriate to the training goals. The trainees are primarily MDs and MD/PhDs who desire careers in investigative endocrinology and academic medicine, as well as PhDs who want further research training. The trainees are selected from a large applicant pool on the basis of prior academic and/or research achievement and evidence of strong commitment to a career in biomedical investigation. The Program Director (K. Miller) and the Associate Director (J. Florez) are senior Physician-Scientists who govern in conjunction with the Endocrine Division Education Council, a committee of experienced endocrine scientists. The faculty consists of 42 active, well-funded scientists, whose interests range broadly across the subdisciplines of endocrinology and from clinical, bedside investigation to genetic and molecular mechanisms. The trainees are supervised closely by a primary faculty mentor, and interact extensively with junior faculty, who often serve as co-mentors. In addition, individual Scientific Advisory Committees provide ongoing scientific and career counsel. Internal and External Advisory Committees provide evaluation and recommendations for Program improvement. Formal Program and Mentorship trainee surveys and frequent (at least twice annual) one-on-one meetings between the Program Director and trainees provide specific actionable input re: the Program and mentorship. An extensive program of didactic sessions complements the research activity. This includes several weekly scientific series, including Endocrine Grand Rounds, and a monthly Career Development didactic series designed for the Training Grant trainees specifically. The productivity of past trainees during training has been very high overall, as judged by the number and quality of trainee publications, number of trainees who obtain subsequent grants and percent who remain in academia and the biotechnology/pharmaceutical industry. The facilities at the MGH and Harvard Medical School are extensive, including a Division of Clinical Research, Harvard Catalyst Clinical and Translational Science Center (CTSC) program and over 50,000 square feet of modern laboratories dedicated to endocrine training faculty. This training grant is the central stabilizing financial element in this program and is critical in enabling MD and MD/PhD trainees to achieve careers in biomedical investigation.